Adding firewall_dns_info() and the ability to set a hostname as source/destination

The following two scenarios are now possible:
   Implicit resolving:
      firewall::rule { "name":
        source          => "$::fqdn",
        destination     => 'example42.com',
        destination_v6  => [ 'example42.com', 'he.net' ],
        protocol        => $proto,
        port            => $port,
        action          => 'allow',
        direction       => 'output',
      }

  Explicit Resolving:
       $dns_info = iptables_dns_info('www.gmail.com')

      firewall { "name":
        destination       => $dns_info['ip_v4'],
        destination_v6    => $dns_info['ip_v6'],
        protocol          => $proto,
        port              => $port,
        action            => 'allow',
        direction         => 'output',
	resolve_locations => false,
        enable            => $dns_info['enable_v4'],
        enable_v6         => $dns_info['enable_v6'],
      }